An exploratory study to investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in adult males.

PURPOSE: To investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in a cross-sectional sample of adult males. This study utilizes several emerging biomarkers that have been associated with early joint degenerative changes; serum COMP (cartilage oligomeric matrix protein), HA (hyaluronan) and lubricin. METHODS: Eighty-one males (age: mean (range): 43(18-70) years; body mass index: 25.2 (21.0-30.6) kg/m2) volunteered. Resting serum COMP, HA and lubricin concentrations were determined via commercially available enzyme-linked immunosorbent assay (ELISA) and femoral trochlear cartilage thickness via supra-patellar ultrasound imaging. Physical activity levels were assessed using questionnaires. Statistical analyses were performed using correlation and regression analyses. RESULTS: Age was correlated with lateral trochlear cartilage thickness (r = - 0.372; p < 0.01) and serum COMP (r = 0.342; p < 0.01). 7-day physical activity was correlated with serum COMP (r = 0.357, p < 0.01), and 12-month physical activity with both lateral trochlear cartilage thickness (r = 0.340, p = 0.01) and serum HA (r = 0.296, p < 0.05). Regression analyses revealed that age significantly accounted for the variability in lateral cartilage thickness and serum COMP, following the adjustment for potential cofounders. However, the association between age and lateral trochlear cartilage thickness was not moderated by physical activity levels (all p > 0.05). CONCLUSION: This study indicates that older age may be associated with thinner lateral trochlear cartilage and higher cartilage turnover. Being physically active may also be positive for lateral trochlear cartilage thickness. However, overall, both age and physical activity level only account for a small amount of the variability in cartilage thickness and serum biomarkers.

The effect of vigorous running and cycling on serum COMP, lubricin, and femoral cartilage thickness: a pilot study.

PURPOSE: Our aim was to investigate lubricin, cartilage oligomeric matrix protein (COMP), and femoral cartilage deformation in response to different biomechanical loading of the knee joint (running vs cycling). METHODS: Serum lubricin and COMP concentrations (enzyme-linked immunosorbent assay), and femoral cartilage thickness (suprapatellar transverse ultrasonography) were determined in 11 male runners (age: 40 ± 6 years; weight: 76 ± 8 kg) and 11 male cyclists (35 ± 12 years; 75 ± 5 kg) at baseline, immediately after, and 30 min after vigorous exercise (time trial: 10-km run or 25-km cycle). RESULTS: At baseline, lubricin (runners: 104.0 ± 19.8 ng/ml; cyclists: 119.1 ± 23.9 ng/ml) and COMP (runners: 804.1 ± 87.5 ng/ml; cyclists: 693.0 ± 84.7 ng/ml) did not significantly differ; however, vigorous exercise was accompanied by an increase in lubricin (cyclists: 39.4 %; p < 0.05; runners: 56.9 %; p < 0.05) and COMP (cyclists: 32.1 %; p < 0.05; runners: 14.2 %; p = 0.14) that returned toward baseline following 30 min of rest (p < 0.05). No between-group differences were observed for baseline cartilage thickness at the intercondyle notch, medial condyle, and lateral condyle, and vigorous exercise did not result in significant change for either group. CONCLUSIONS: In the absence of ultrasonographic knee cartilage deformation, the response of serum lubricin and COMP following acute vigorous exercise indicates an increase in joint lubrication and cartilage metabolism, respectively, which appears largely independent of exercise modality.